Straightforward trunking system



Sept. 6, 1927.

,641,218 R. s. BAILEY S TRAIGHTFORWARD TRUNKING SYS TEM Filed May '7. 1924 5 Sheets-Sheet l Y 1,641,218 sep1.s,11 z?. RS. BAILEY STRAIGHTFORWARD TRUNKING SYSTEM Filed May 7. 1924 3 Sheets-51191112 R. s. BMLEY Sept. 6,1927.

STRAGHTFORWARD TRUNKING SYSTEM i Affy 3 Sheets-Sheet 5 vena/f. /Pm 9m/@y il Patented Sept. 6, 1927.v

U NITE D AT ES.

PATENT oFFlcE.

. RAND s. BAILEY, or MoNmcLarn, NEW JnasaY, AssIGNon To AMERIGAN'TELEPHONE AND Tannen-Aan contraria', A oonPonATIoN or NEW YORK.

f sTnArGi-rrnonwfinn TRUNKING SYSTEM.

Application area' May '7,

lThis invention relates to telephone systems, and more particularly, to trunk circuits for establish-ing connections between ymanual telephone exchanges. Y

In manual vtelephone trunking systems as at present arranged, it is customary for the so-called B operator at a'dstant office to assign, by means of a separat'eforder wire, a trunk to berused by the so-called A operator at the call originating oi'iice for theex? tension of a connection to the distant otiice, and keys are ususally provided whereby the B operator may connect her telephone set to the assigned trunk for Vthe attention and supervision of the call*v It is an object ofthis invention to yeliminate assignment of a trunk bythe B op- 4era'tor by the provision of a@ so-called V'straightforward trunking system, whereby the A operator may seize any trunk leading to the vdesired distant ofhce and whereby vthe B'y operators telephoneV set is automatically connected vto atrunk the moment it is seized; Y i

Another object of the invention is to provide suitable vsupervisory signal indications.

jacent operators ateither side may take over and attend to calls at such Van operators attention at their own'positions. l

Another obgect is to 'proyidean emergency arrangement whereby the B operators setl may be manually connectedto the trunks if the automatic equipment is incapacitated.`

To attain these objects in accordance with one feature of this invention, a multi-com' tact relay and circuit arrangement is provided whereby the B operators set is automatically connected to afytrunk the moment it is seized provided the set is not already engaged, in which case, the yseized trunk is held ready to be connected when the set is free.-

Another feature is the provision of asocalled group relay an unit relay arrangement position when there are no calls awaiting" 1924. Serial No. 711,691.

by means of which the trunks are divided yintogroups soarranged in cooperation with kthemulti-contact relay that the seized trunks lare connected to the B operators set 4in accordance with the value of the arbitrary numbers assigned thereto, ,that is, a seized trunkr located'inv a group having a lower number would be attended to before a seized trunk located in a group having a higher number and so also would a lower numbered trunk ina .group be attended to in prefer- `ence 'to a.v higher numbered trunk in the lsame group.

- associated with each trunk, whereby if such key is depressed thecorresponding trunk is disconnected from the. B operator norm ally assigned to attend to 1t and connected `to an adjacentoperators set, that is, adjacent operators can at will attend to and dispose of incoming calls at each others positions. Y

Another feature resides in the provision of a signal operating arrangement whereby a signa associated ,with a seized trunk is operatedin one 'characteristic manner when the B operator normally attending to the trunkis connected thereto and in a different characteristic manner when `an vvadjacent operator is attending to the trunk.

'()tlier Vfeatures reside in the operation of .the si gnalsI associated with the trunks to in- 'dicate the progressof a call. y Another feature is the provisionof an lemergencykey at each B operators posi `tion byrmeans of which, if the automatic at one exchange and also a trunk line terminatingfin this exchange and extending to a B operatofsposition at a distant.V exchange where va called subscrlberis line is also shown. Fig. Zillnstrates aftype of multa-contact tit! relay arrangement used in connecting the B operator-"s telephone set to trunks, such as the one shown in Fig. 1, and the associated group and unit. relay arrangements t'or the preferential service.

Fia'. 3 shows emergency keys and associated relay arrangements Ylor three adjacent opcrators positions. The drawingr should be arranged together by placingl Fig. 1 above and Fig'. 3 below Fig. 2.

The sy'stcin disclosed in the d'awings is devised in such a inanner that a B operator at the heine position is capable ot' handling calls incoming to her position on L1S) trunks, though it is obvious that, should conditions require it` the equipment niay be readily adapted to handle a greater number oi. trunks.

The l trunks are divided into seven groups, each group having seven trunks therein. For descriptive purposes only, the trunks in the first group are numbered :troni 11 to 17, inclusive, the trunks in the second group troni Q1 to 2T, inclusive, and so on to the last group, wherein the trunks are nuinbered Tl to TT, inclusive. Each of the groups ot' trunks, that is, all trunks bearing the saine tens digit such as trunks l1, 12, 125 1T which hereinatter shall be referred to as the vertical groups. have alloted to theiu a pair ot tens group relays, and these `rroup relays are arranged iu a chain circuit` in such a manner as to ettect a vertical group preferential circuit, and the system is so arranged that the lower number groinis have yne'terence over the higher number groups, that is, the trunks in the vertical group bearing the tens digit 1 have pre-terence over the trunks in the vertical groin) bearing the tens digit 2, etc.

In like nlanner, each `group (which will hereinafter be re't'erred to as the horizontal groups) ol trunks bearing the saine unit digit such as trunks 11, 21, 31, etc., has allotted to it a pair oi unit group relays. the unit relays ot each group being also arranged in a chain circuit so as to ef'i'ect a unit iiufcterential circuit, and the system is designed so that the trunks in the horizontal groups bearing;n the lower unit digit have *preit'erence over the trunks bearing higher unit digits. that is, trunk Q1 has preference over trunk *22. etc.

The ilnulti-cont-.ict relays employed in the system disclosed and shown in Fig'. 2, are in substance, relays which in operating close theiiicontacts on stationary busbars. so that to handle the t0 trunks specified, only seven ot such bus-bars are required, each set being connnon to the seven trunks in the sante horizontal group, such as the trunks 11. 21, 31, etc., that is, the first set of busbars is assigned to the trunks 11, 2l 31 71, the second set of bus-bars to trunks 12, 22, 32, 72, etc., and all the sets are comn nien to the B operators telephone set at the holne position. ln this inai'lner, by the `ioint operation ot a set ot tens group relays and a set ol'A unit group relays, the .ti operatoi"s telephone set niay be connected to any one ot the i19 trunks ii'icoining at her position.

The, invention will be readily understood from the following' detailed description.

The iirst description will be directed to the establishment of a connection between a calling,r subscriber at station D and a called subscriber at station lll, the connection to be established by way ot an A operators cord circuit C and, the `trunk T, which :tor descriptive purposes will be assumed to be trunk No. 11, that is, the lirst trunk in the tirst vertical trunk group.

The subscriber at station A upon reinov ing the receiver troni the switehhook, causes the line relay 100 to operate over an obvious circuit. Relay 100 in operating, causes the line lanip 101 to be lighted. The operator at position C) at which the line lamp 101 is located, upon notingl this lainp lighted insert-s the answering plug 102 ot' a cord circuit (l into the jack l0?) associated with the illuminated liney laiup 101. Upon the in. scrtion ot' pluri' 102 into jack 103, the answerin;Y supervisory relay 101 operates Atroni battery associated with the repeating coil 132 in a circuit including,l the closed subscribei"s line loop and the answering end ot the cord circuit' C. relay 10iA operating in this cir cuit, connects the resistance elenient 105 in shunt of the answeringl supervisory laiup 100, preventing this lamp l'roin light-ingl over the sleeve circuit which is now closed. The cut-otl relay T operates in the closed sleeve circuit, disconnecting the line relay 100 troni the calling subscribei"s line. The line relay 100 thereupon releases, causing the line lanip 10i to be extinguished.

The A operator then actuales the key 10th thereby bridging: her telelihone set indicated at O. T. across the tip and ring coiu'luctors ot the cord circuit. The operator then requests. ot the calling: party, the desired nuin` ber. Upon learning' that the desired party is located at station E, the, A, olierator ter. s for an idle trunk leading; to a l?) operators position, at which the desired line terminates in the jack 100, in the weil known manner and on finding` the trunk T. which is assumed to be trunk nulnber 11. idle, she inserts the plug 130 into the jack 131 ot the selected trunk.

Upon the insertion of: plug: 1530 into jack 131, a circuit is established which nlay be traced t'rrnn Lgrounded battery, through the lower right-hand wiudin5 r ot nepeatingr coil 132, winding of supervisory relay 13?), ring contacts of plugr 130 and jack 131. lower lett'- hand winding ot repeating' coil 153i, lett hand high resistance winding ot relay 135, upper left-hand winding of repeating coil lltl . cuit.

134,-tip contacts ofjalck 131 and plug 130, through the ,upper right-hand 'Winding of repeating coil ,132, lto ground.V Due to the high resistance ofthe left-hand winding of relay'135` included in this circuit, relayV 133 does not operate at this time, so that the supervisory signallamp 136 will light in an obvious manner through the sleeve eircauses the assignment lamp 157 to be lighted in aV circuit Awhich may be traced from grounded battery, through the resistance element 158, front Contact and left-'hand armature of relay 139, t ground through the filament of lamp 157. The assignment lamp 157 glows steadily in this circuit, indicatto lthe B operator `that there is a call waiting on the trunk T. YAt its armature .142, relay 139 causes currentfrom the. tone source 200 to be connectedrto the tip conductor ,of the trunk T. The connection of this tone current to the tip conductor of the trunk causes a tone totbe manifested in the A operators head-set, indicatingto the A operator that, the B operators telephone set 4is not yet connected to the selected trunk.

It is understood that the B operators telephone set" is assumed to be idle at this time.

At its armatures v151 and 143, relay 139 closes through the common leads 280,290 and 220.

A circuit maynow be traced from grounded battery, over the rlght-hand armature and` back contact of relay 315, back contact and lower armature ofv relay 316, armature and back contact of relay 217, resistance element 218, back contact and upper armature of relay 219, normal make-beforebreak contacts'v of group relay 202, winding of relay 202,V winding of group relay 201, common conductor 220, front contact andarmature 143 of relay 139, to ground. Thefgroup yrelays 201 and 202 which are allotted to the first vertical group of trunks Nos. 11 to 17 inclusive, operate in this circuit. Relay 201 in attracting its outer armature, opens the shunt circuit including contacts 4of all other vertical group relays. At its innery armature, relay. 201 prepares a circuit, the completion of which will presently be described. j

Relay 202 at its right-hand armature, con- Y, 4nects lground to the winding of the group l relay 221, byyvayof the inner armatureand front l'contact of relay 201. Relay 221 thereupon operates toclose all its contacts on the seven sets o'fbusf-bar's" iriiniediately'bova it for.'I JrurposesA which Will hereinafter appear.

.At its left-handy armaturarelay 202V 'opens the original energizing,circi'i'it'Y for relays201 and 202fand substitutes another` circuit therefor, Y:extending through thei winding A,of

relay 217. i Relay 217 thereupon v'operatesand Y `in attracting its armature also opensat another point the v originall energizing Acircuit for 'relays 201 and 202 and causes relay 219 to operate in* a circuit Whi'ch'is believed to be obvious. In attracting its upper armature, relay l219 transfers Vthefsta'rt lead 289 to the baolrcontact' and outer armaturer of relay 213, which is one ofthe group Vrelays 'assigned to the seventh vertical ygroup of This trunks (Nos. 71 to 77 inclusive).- transfer is eectedfin `order tomaintain the order of progression Vso long4 as there `are calls Waiting, as Willbe more fully described hereinafter. Relay 219` is made'slow to release to further insure this order of progression. The closure of thecontacts 282,

283,' and 284 of the multi-contact-relay 221,

connects the kconductors 292, :1293, and 294 rwhich are:individualto No. 11 tr-unl`T,-Yto

the setlv of stationary bus-bars which set Vis individual tothehorizontal group oftrunks (Nos. 11, 21, 31,41,"51, 61- and` 71)..; At thercontact240, relay 221 causes relays'217, 201 and 202 to lockv through Athe bus-bar 241 which is groundedv at the-contacts of the position release relays 242 and 243.

The unit vrelays 261 and 251 now. operate in a circuit Aextending from grounded "battery, through the resistance' element 250,

, back contactvandarmature of relay 260, normal make-before-break contacts of-rlelay261, Winding of yrelay 261, winding of relay 251,

conductor 280, armature 151 and frontl con-.v

tact of'relay 139, conductor290, fro'ntfcontact andv inner armatureV of.relay 201,'1-,to ground vover the front contact and righthand armature of-rela'y 202.; Relay 261 .in operating, opens the originalenergizing circuit for relays-251 and 261 and connects relay 270 in lseries with these relays rtobattery and ground, causing relay 270 toy operate andestablish an obviousicircuit for relay 260, which in operating transfers the start lead 291 to the back `Contact of relayl 257, which'is one of the unit relays allotted to the seventh horizontal group of trunks.` ln this manner the order ofprogression is maintained asl hereinafter described.-v Relay251 also closes fall its upper contacts to the lseventh setof stationary bus-bars. At the contacts 271, `relay 251-causes relays 270, 261 and 251 to lock through on the bus-bar 241 which, as hereinbefore stated, vis groundedby Way ofthearmatures and 'contacts oflthe position release'relays 242and 243. At its contacts, 1272, 273 and 274, relay;V 251 causes the' leads'295, 296'and7297,- which lead to the B pe`rators telephone set, to be: connect-l l' that relay 161 is short circuited by its own normal contacts and by the normal contacts of relay 162, so that this` relay does notA at the subscribers station E, condenser .159,

tip contacts of jack 109 and plug 170, alternate make-before-break contacts of relay 140, to .ground at the upper armature and front contact of relay 160. The bells at the subscribers station are actuated by this current to signal the called subscriber. Relay 162 being marginal, does not receive suflicient current at .this time to operate.

-lVhen the called. subscriber responds to this signal by removing the receiver` from the switchhool, the condenser 159 isl short circuited and'the path for the ringing current is then through thesubscribers switchhook contacts and transmitter; With the condenser 159 short circuited, the resistance of the ringing circuit is sufficiently decreased to permit thetripping relay 162 to operate. Relay162 in operating, opens the short circuit about the winding ol relay 161, permit'- ting this relay to operate in series with relay 160. Relay 161m operating, connects batteryto its own winding, causingit to be locked to ground at the front contact and armature o1" relay .138 and causingthe ringing relay 160 to be shunted to disconnect the ringing current source 163 and the winding of the tripping relay 162 from the ring conductor` ofthe trunk. Upon the release ot' the ringing relay 160, the supervisory relay 152 operates in a circuit eX- tending from grounded battery, through the lower right-hand winding of repeating coil 13-1, winding of relay 152, back contact and lower armature of relay 160, ring contacts of plug 171 and jack 109, through the subscribers closed line loop, tip contacts of jack, 109 and plug 171, alternate make-before-break contacts of relay 140, upperarmature and back contact of relay 160, to ground through the upper right-hand winding ot repeating coil 134, Relay 152 inoperating, connects the right-hand low-resistance winding otl relay 135 in parallel with its left-hand high-resistance winding and in series withA the left-hand windings ofthe repeating coil 134. Due to the shunting of the left-hand high resistance of relay 135, relay 133 now operates and thus short circuits the lamp 136 through the resistance 137 so that lamp 136-now becomes extinguished to indicate that the called subscriber has answered. The connection is now completed between the two subscribers vandconversation mayl take place.

Assuming now that the period of conversation has terminated, thejcalling subscriber at station D replaces theL receiver on the Y switchhook, thereby releasing the answering supervisory relay 104, which in turn ,removes the shunt from the lament of lamp 106, permitting this lamp to be lighted over the cloied sleeve circuit. The illumination of lamp 106 at this time serves as a disconnect signal to the A operator,`who then proceedsto take down the connection by removing the plugs 102 and 130 from jacksV 103 and 131, respectively. The removal of plug `102 from jack 103 opens the sleeve circuit, causing the lamp 106 to be Vextinguished and the cut-off relay 107 to be released., Relay 107y in releasing, reconnects the line relay to the tip and ring conductors of the calling line -When the A operator withdraws plug from jack 131, relay releases, which inturn causes the release of relay 138. Relay 138 in retracting its armature opens the locking circuit for relay 161 causing this relayA to restore, and causes the disconnect relay 155 to operate in a circuit which may beV traced from grounded battery, over the lower armature and front contact of relay 140, through the winding of disconnect relay 155, to ground vat the back contact and armature of slow releasing relay 138. The disconnect relay 155 in attracting its armature 174, locks Linder the control of relay 140. In attracting its'armature 175, relay 155 causes the assignment lamp 157 to be illuminated in a Vcircuit extending from lgrounded battery, through the. resistance element 158, front contact and armature 175 of relay 155, to ground'through the lilament of lamp 157. The illumination of lamp 157 at this time serves as a disconnect signal to the B operator. The operator thereupon proceedsy to remove plug 170r from jack 109 which releases relays 140 and 155 causing lamp 157 Vto be extinguished.

With calls waiting.

It should be noted that in case the A operator attempts torconnect with trunk T before the B operator has had time to complete the disconnecting operations7 the fact that relay is operated will not prevent the bringing in of this new connection'as battery will be supplied through this relay at its right-hand armature and front contact from the lower armature' and front contact of relay 140 for trunk relay 139.. The energization of relay 139 will, therefore. maintain the assignment-lamp 157 lighted and cause it to begin iashing as hereinbetore described after the B operator disconnects and releases relaysV 140 and 155, relay 139 being now maintained energized fromv the battery at the lower armature and bach contact of relay 140 and the lamp again servl IU tit)

ing as an assignment signal 'for a new con neetion to he extended by the .Ll operator.

It will, therefore, he assumed that the l operator has just completed a call on trunk No. lll, as described, and that calls are waiting to be answered on trunk No. li, that is the last or seventh trunk in the lirst vertical group and trunk No. Tl or the tirst trunk in the seventh vertical group. rthe trunk relays lt' and Tl respectively ol these trunks are shown to the lelt ot' Fig. 2 opposite the corresponding trunk hus-bars ol the inulticontact relays, to simplify the description and to render the system niore rei dily understalnlahle. It is to he rcnienibcred that the relays ll and i'l correspond in every detail to relay i239 ot' the No. ll trunk 'l,`, the armatures lts and T2 ot these relayscorresponding' to armature la?) of relay lili) and the arnnitures lt) and T3 ol these relays corresponding' to armature ll oli relay i239. To assist in this comparison. the corrcspending position, relay 139 would have occupied, shown by a dotted outline otE this relay marked ll. Another trunk relay 7T. beine' assigned to trunk No. TT, the last trunk in the seventh group. has also heen shown arranged in a correspondinill position to give a turther clear understandina` ot' the relative arrangement ot' the trunks and the ctn-rospondenee between them and the trunk relays.

Under the condition assumed` the group relays Qtlt and itl?. and the units relays 251 and til are operated and locked to `around at the position release relays .Zll and 2.453. lhe actuation ol` the inaster release key llt releases the relays dal and Ztl, hut relays Qtll and i202 cannot release at this time, since there is a parallel holdingl circuit to ground on the arnnitnre 1S ot' relay li' which relay is individual to trunk No. 1T on which We have assumed a call to he 'aitina'` Relays Q01 and 202. therefore, remain operated and upon the relei se ot relays 251 and 261., rei lays T and 26T operate in a circuit ex tt'ifndiiu;` il'roin grounded battery` throue'h the resistance element lot). hack contzulit and armature o't relay 260, start conductor 291,. over the chain circuit' including: the normal inahoteliere-break contacts of relays Qtl to Qtit. inclusive. and the back contacts and ai inat'ures otl relays to i256. inclu -sive. then over the noi-naal 1nalie-bciore-lnfcak contacts. of relay 26T. Winding ot relays 26T and 25T. conductor Q77. armature i9 and Alront contact oll relay 1T. l'ront'l contact and inner arinature ot relay 01. to ground at the 'tront contact and right-hand armature oi relay Q02. Relays and Q67 which are allotted to the seventh horizontal igroup ot trunks operate and lock to ground at the contacts of the position release relays 242 and hy way of the contacts 22S of relay Q5?.

lt should he noted here that il the B operator is slow in releasingl the position key 2li, she in no way atlccts the operation ol the, next: call since the master p'round is restored innnediately, irresptactive ot the length ot. the interval during which the key il is actuated. lhis accoinliilished by the contact arrangennfnt and relative open atingl elniracteristics oil the position release relays i242 and llll as hercinbetore described. lielay 257 in closing` its contacts 23:58. 24:8 and :258. performs the saine functions as des scribed in connection with the closure oi' contacts 27:2. Q73 and :27+ ot relay so that; the l operators head set is now connected tio trunk 'lT by way ot the conductors i295 and .Ztit, contacts 23S and M8 of relay Q57, tip and ringr hns-hars ol set i', contacts 22) and 553i.) ot group relay S5321. and thence to the tip and ring@T conductors ot the trunk No. 17 by ivay of coinluctors corresponding to the conduetors 292 and 293 ot No. ll trunk T.

Had there been other falls Waiting` on trunks such as l5 or lG o'l the lirst vertical group, these calls would have been completed hefore the call ou trunk ll was completed and the call on trunk lo would have the preterence over the call on trunk 1G. This units piaiterencc is accomplished by virtue ot the tact that after the unit relay 2.5i has released due to the actuation of the position release key QM, a circuit for relays Q and 205,

`which relays are allotted to the fifth horii '/:ontal group ot trunks containing),` trunks lo, 25, Ila, a5, 55, (35 and T5, is established 'from grounded battery, Winding of relay 270, armature and front contact of relay Qtl, armature and back contact o' relay 251, normal make-befoie-hreak contacts and hack contacts und armatures of relays 262, 263 and Qtl and and 25a, respectively, through the windings of relays 255 and 2Go. in series, and thence over the conductor 2o to the right-hand armature and front eon tact ol" the No. l5 trunk reiay which relay corresponds to relays such as 139 and 17 and which arnniture corresponds to armatures such as ll and 19 ot' these last mentioned relays, respectively, front contact and inner right-hand arniatin'e of relay 201 to ground at the front contact and right-hand ar1nature ol relay 202 which relays lOl and 202 are niaintained operated as hereinhetore mentioned. Then relays and 265 operate, the chain circuit for relays .256 and 266, which relays are allotted to the sixth horizontal `group of trunks (Nos. 16, Q6,

To) opened preventiim` these relays 'trein operating. ln `this inanner the B operator-"s telephone set is connected to trunks ll to lT, inclusive, of the lirst vertical group in sequence if calls are writing` on these trunks and not until there are no calls Waiting in this group Will the operators telephone set be advanced to the second vertical group of trunks.

dal

lUtJ

isa

As has been assumed the only calls waiting when the call on'trunk 11 was completed,

.- trunk No. 17 is taken care of, the next description will be directed tothe completion of a call waiting on the trunk No. 77.

When the irst vertical group has been satisied and no other calls are waiting, re-

lays 201 and 202 will` release upon the actuation of the position release key 244 since there isnow no parallel holding circuit for these relays, the relays 11 to 17 being now in their normal positions. Upon release of the 1'; relay201, relays 213 and 214, which are allotted to the seventh vertical group of trunks (Nos. 71 to 77, inclusive) operate in a circuit extending from grounded battery, over the right-hand armature and back contact of relay 315, back Contact and lower armature of relay 316,y Winding ofrelay 217, left-hand armature and front contact of relayV 202, outer right-hand armature and back contact of relay 201, normal makebefore-break contacts of relays204, 206, 208, 210 and 212 and outer armature and back contacts of relays 203, 205, 207, 209 and 211, respectively, `windings of relays 214 and 213, to ground on the front contact and left-hand :f armatureof relay 77 which relay is operated ydue to the waiting call on trunk No. 77;

Relay 227 now operates in a circuit extendving from grounded battery, throughthe winding of relay 227, frontA contact and inner armature of'relay 213 to ground at the front contact and right-hand armature ot relay 214. In attracting its left-hand armature relay 214 opens the chain circuit to the other group relays and causes relay 217 vto operate in series with relays 214 and'213,

in a circuit which is now believed to be obvious. In this manner when relay 219 inally releases after all calls in the seventh vertical group have been completed the iirst vertical "1 group of trunks will have the preference over all other vertical groups. The units relays 257 and267 `now operate in a circuit extending fromV grounded battery, through `the resistance element 250, back contact and armature of relay 260, conductor 291, normal make-before-break contacts of relays 261 to 266, inclusive, and contacts of relays 251 lto 256, inclusive, respectively, winding of rela ys 267 and 257, conductor 277, right-hand armature and front contact of relay 77 to. ground over the armatures and front contacts or relays 213 and 214. u f, Q

y `Relay 227 operating as hereinbefore described, connects the ground associated with the armatures'and back contacts of the position release relays 242 and 243 Vto the lower bus-bar of set 7, whereupon relays 214,213, 217 and 219 lock in the same manner as described in connection with relays 202 vand 201 lunder thefcontrol-of the position release' relays 244- and 243. When relay 267 operatesit opens the chaincircuit in all other units relays and causes relay 270 to operate in series with relays 267 and 257. Relay 27 0 causes-relay 260 to operate. When relay 257 closes its lowerinost contacts it causes relays 260, 270, 267 and 257 to lock under the control of and u Y With relays 227 and 257 operated as describedthe B operators telephone set O. T. is connected to the No. 77 trunk in a circuit which is now believed to be obvious.

Had there been calls waiting on any other vertical 'groups of trunks such as the second or third vertical groups these calls would have been completed before the calls waiting in the seventh group and the calls in the second group would 'have preference over those Waiting in the third group. This group preference is obtained in the same manner'as hereinbefore described in .connection with the units. preference.

F rom the foregoing'description itis apparent that theapplicant has devised a systern wherein the lower numbered trunks in each vertical group have preference over the higher numbered trunks and the lower numbered vertical groups of trunks have preference over the higher` numbered vertical groups of trunks and the B operators telephone set isv not advanced to the next succeeding vertical group vuntil there are no calls waiting in the vertical group wherein the Alast call was completed.' f

Team/work.

It the E operators telephone set is engaged at a'time another call comes in on anposition arefconnected so that the operator on the leftof this position may attend to the sa1ne,'whereas those on the right of the position are connected so that the operator' at the right thereof may attend tothe same. 1nr other words, the first twenty-live trunks beginning at 11 may be attended to by the the position release relays 242y operator on the left, while the remaining trunks 'may be attended to by the operator on the right. Therefore, should an operator at a position adjacent to the home operators positiomtor example, the B operator on the lett, upon noting the steady illumination of an assignment lamp such as 157 ot' No. 11 trunk T desire to relieve the home operator ot answering this call, she may do so by reaching over to the home operators posiv tion and actuating the, team key 180, that is individual to the trunk T. Upon actuation ot' this key a circuit is established trom grounded battery through the winding of relay 31T associated with the equipment at this adjacent operators position, conductor 38T, lower armature and hack contact of a relay at this position corresponding to relay 21S) ot the home position, conductor 386, conductor 385, inner lower armature and back contact of relay 316, conductor 191, inner right-hand armature and front contact of relay 153i)A winding ot' relay 19t)` key 1S() to ground. Relay 19() operates and at its armatures 12T and 12S locks independent of the team key 18() and the trunk relay 139. At its two outer righthand armatures and front contacts, relay 15)() connects the tip and ring conductors 182 and 181A) tlnough the normal contacts of the emergency release key 300. conductors 301 and 302 which are strapped at the emergency release key 325 to the tip and ring conductors 3% and C327 leading to the telephone set of the B operator on the lett ot the home position as these conductors correspond to leads 202 and 52023 of the home position. This particular' trunk T at the home operators position is now therefore directly connected to the tele phone set of the B operator on the lett.

0n the other hand. it, :tor example, a B operator on the right should notice the steady illumination ot' a. lamp, such as 15T o't a trunk other than the trunk T in the group assigned for her attention she may depress the team key corresponding to 18() ot that trunk and extend a connection to her set as follows: from this truuk to the tip and ring conductors 3l() and 311 through normal contacts ot emergency release key 300, conductors 342 and 3&3 strapped at the einergency release key 35() ot' the adjacent operator` tip and ring conductors 344 and 2115 to the telephone set of this operator. It is thus seen that hy this arrangement any operator may assist the operator on either side of her position and Afurther. that the operator assisted is notitied of lthis tact by the flash ing ot the assignment lamp" in a manner dilierent from the flashing established when her own set is connected to the seized trunk. This flashing is done as follows: when the circuit for relay 19() was closeth` a relay 317 was also operated completing a circuit; for relay 318 and the operation of relay 318 in accordance with interruptions produced by the interruptor 82() establishes a flashing shunt circuit for lamp 15T as follows: from `ground at the armature and front Contact of relay 318, upper armature and back contact ot relay 31th conductor lifh inner righthand armature and 'trout contact, ot relay 11)() to the lamp 15T.

Provision is also made in this inventionj whereby an operator is prevented troni assisting an adjacent operator as long as there are calls waiting.; at her own position. lt will be noted that the energizing circuit tor relays 190 and 2317 passes through the lower arruature and back contact ot a relay corresponding to relay dit) and as this relay is always operated when a call at the corresponding` position is awaiting attention, no circuit can therefore be established `lor assisting an adjacent operator, eren thtnuijh a particular team key may be accidentally or otherwise operated.

Emergency Service.

In case the multi-contact relays or any part ot the preferential relay arrangement should tail to operate there is provided in zucordance with this intention a circuit arrangement including thc emergency key and the team keysl i'or establishing connection between any trunk and the operatoi"s` set, that is, these keys are used as ordinary trunk listening keys in the manual trunk circuits where the operations set may be di rectly connected. Should,` therefore, the circuit arrangement itaih the emergency key Btl() is depressed and when a call comes in as signified by the lighting ot an assignment lamp such as 157, the operattu' simply depresses the corresponding team key. rlhe operation otl the emergency key 30() closes an operating circuit for relays 316 and 351 and the operation ot a team key such as 18() closes a circuit as follows: battery, winding ol' relay 315, conductor 352, lower armature and back contact of relay Q19, outer armature and back contact ot release relay 242, conductor 302, lower armature and 'front contact of relay 316, conductor 191, inner right-hand armature and 'front contact ot' relay 13), winding ot relay 19t)j key 18() to ground. Relays 19() and 2315 are operated in this circuit. The operation ot relay 19() connects the operato1"s telephone set to the trunk T over conductors and 38:1 through emergency release key SO() over conductors 182 and 183. armatures and front contacts of relay 19() to lett side ot repeatiiig coil 13a. The operation ot relay 316 completes a lashing circuit :tor assignment. lamp 15T from the busy-back interruptor filo() connected at the upper armature and front contact of relay 316 by way ot lead 52:2, inner righthand armature and front contact ol relay 19() to lamp 15T. to indicate to the operator that her set is connected to the trunk. l't should be .noted that at the operation of relay 316 the circuit for thc group relays and relay 21T is opened at its lower armature and back Contact`to positively prevent the ltlll ae'e'einplished th v "key 2.45:; the" Sama las W1 n @he Se' s'efaeesjubseqa a operation'there9f.. Astated ough opeifatofsj set fiioin "tiie 'l uiik they dispesaifff :aeciniiiilaJ v thaadjacerrb' Operate@ Cai. assist the 0' eratr `having *hery emergency Ip is'evidennthat with meifgency *key* l1in this operai e adjacent-@Senatoi raie:

lo I connectV theibperatos tele-Y i perating: said signals -Ineaiis operato means l tnn'eet L11' evv seeon'di eperatorfs `:telephone in'gfto che fseen'd operator th'at' a tirnnkilinef has been seized, signaling meansfmr-'indicate sto '.jth'e second :'.operator -tliatz--Alieif` te1ephonei Ysetrhas. been? iqonneeted fete said; seized trunk, and; signaling vinea'ns :foi indieating tov'th'e iii-'st bpe'vatoi that the second-,operator tifu'nk isfseizedffor :automatically,connecting said'fnp'eiatorsetelphbneset fte saidfseized trunk; fm'eansff'fzon' loper-.ating f said' connecting in e'anst honneetf the? srseeon'd operators Ytelenphneset' tof: Subsequently i seized I trunk-y lines a Yseized before/the first'fnentined trunk {line-@isf 'disenneeted 'fvoni .thegfoperators set lfegaifdfless T(if: lie? Order, tin: which the* trunks varevvv seized 'a 'si'grnalf freaehitrunkfline; each t'o" subsequenjgiy seized trunk flines vin; az

leiief; seti is 'connected'F to l the i 1'la?lpiedetermined'lordeiffif: said ttrunk: fl-ines Y I A ioberatedfwhefthe@corresponding trunk line -ifsff`:sei 'zed toffinfdieatetiefA bh; secondroperator Zih'alt "sue-'1h' seizurehastakemplace; means -for eperatiigfanyfzone f of .f said signals" in a dif'- 'ferentfamanneif when the second Y'zopei'acolfs :frei'a'tingy said Gtnefdevicefwith,-; any fof -5- said trunk-i linesV when seized-s tof indicate ,to'f fthe -iis't 2 eratorfth't thefsecend -pelatonisset is not yet connected to said seized trunks, and means tor disconnecting said tone device from a seized trunk when the second operatorie telephone set is connected thereto to indicate to the lirst operator that this connection has been made.

ti. A telephone system comprising trunk lines, an operators telephone set, means for seizing any one ol said trunks, means operatire when a trunk line is seized for automatically connectingr the operators telephone set thereto, means Afor disablingsaid automatic connecting means and manually operble means ell'ectiye only upon the actuation ot said disabling means for connectingr the operators telephone set to any one of said trunks when seized.

7. A telephone system comprising trunk lines-` an operators telephone set, means 'for seizingr any one of said trunks, means operatite when a trunk line is seized for automatically connecting the operators telephone set thereto, means tor preventing the automatic-connecting means from functioning when a trunk line is seized, and manually operable means individual to each trunk line for connectingr the operators telephone set to any seized trunk, said means being effective only upon the actuation o't said means for preventing the automatic means from functioning.

`8. A telephone system comprisingtrunk lines, an operators telephone set, means for seizing any one of said trunks. means operative when a trunk line is seized for antomatically connectingr the operators telephone set thereto, means comprising a plurality ot keys and a relay arrangement associated therewith whereby the depression of one key disconnects the automatic connecting means and whereby the depression of an indii-idual key associated with each trunk line connects said trunk line to the operators telephone set provided said trunk line has been seized.

S). A telephone system comprising;r trunk lines, an operators telephone set, means tor seizing;r any one ot' said trunks, means operative when a trunk line is seized for automatically connectingT the operators telephone set thereto, a key common to all trunk lines, a plurality of keys each individual to a trunk line, and means operated when the common key and a key individual to a seized trunk line are operated to disable the automatic connecting means and connect the seized trunk to the operators telephone set.

10 A telephone system comprising trunk lines, operators positions, means for seizing any one of said trunk lilies, means at each position for automatically connecting the corresponding: operators telephone set to each seized trunk terminating at said position, and means located at one position for manually connecting the operators telephone set located at an adjacent position to a seized trunk line terminating;r at said first mentioned position.

ll. 1i telephone system comprising trunk lines, operators positions. means ior seizing any one oll said trunk lines, means at each position Alor automatically connecting the corresiiondingi` operators telephone set to a seized trunk terminating at said position, and means individual to each trunk line atone position and located thereat for connectingr the operatoi"s telephone set located at an adjacent position to a trunk line it said first mentioned position ii said trunk line is seized.

l2. A telephone system comprising trunk lines, operators positions, means for seizing,l any one of said trunk lines, means at each position for automatically connecting the corresponding operators telephone set to a seized trunk terminating at said position, means located at one position for manually connecting the operators telephone set located at an adjacent; position to a seized trunk line terminating at said first mentioned position, and means operated. when an adjacent operators telephone set is so connected for preventing the automatic connecting` means at said adjacent operators position from operating when a trunk line terminating thereat is thereafter seized.

12%. A telephone system comprising,l trunk lines, operators positions, means for seizing any one of said trunk lines, means at each position for automatically connectingl the corresponding operators7 telephone set to a seized trunk terminating at said position, means at. one position tor manually connecting;- the operators telephone set at an adjacent position to a seized trunk line terminating; at said lirst mentioned position, and means at said adjacent position ttor preventing said manual connectingl means at the first position from operating it a trunk circuit at an adjacentposition is seized and connected to the operators telephone set thereat. l

les. A telephone system comprisingr trunk lines, operators positions, means i'or seizing any one ol said trunk lines, means at each position for automatically connecting the corresponding operators telephone set to a` seized trunk terminating at said position, means at one position lor manually connectingr the operators telephone set at an adjacent position to a seized trunk line terminatin?,` at said lirst mentioned position, and signaling' means associated with said seized trunk line operative when so connected to indicate to the operator at the first mentioned position that the trunk is connected to an adjacent operators set.

l5. A telephone system comprising trunk lines, operators positions, means for seizing any one of said trunk lines, means at each position for automatically connecting the corresponding operators telephone set to a seized trunk terminating at said position, means at one position for manually connecting the operators telephone yset at an adjacent position to a seized trunk line terminating at said rst mentioned position, a signal associated With each trunk line, means for operating any one of said signals in one characteristic manner when the corresponding trunk line is seized, and means for operating any one of said signals in a different characteristic manner when the corresponding seized trunk line is connected to an adjacent operators set to indicate to the first mentioned position that the trunk line is so connected. Y

16. A telephone system comprising trunk lines, an operators telephone set, means for seizing any one of saidtrunk lines, means operative When a trunk is seized tor automatically connecting the operators telephone set thereto, means for disabling said automatic connecting means and for manually connecting the operators telephone set to any one of said trunks when seized, signaling means for indicating in one characteristlc manner to the operator that a particular trunk line is seized and in another characteristic manner that the operators telephone set is connected to the saidtrunl; regardles of whether it has been connected automatically or manually.

In testimony whereof, I lhave signed my nameto this specification this 6th day of May, 1924.

RAND S. BAILEY. 

